Unfortunately, the filestore cannot be regenerated from the .dump file alone, because the .dump only backup the database, and Odoo stores binary attachments (e.g., uploaded files, images) outside the database in the filestore directory located under: 

~/.local/share/Odoo/filestore/<dbname>/

so in the case you backup using the dump file it will not include the attachment file there, thefore you cannot get the attachment file when you restore it.

what you can do: 

before you restore, you should create a backup copy of your filestore directory in 

~/.local/share/Odoo/filestore/<dbname>/

then after you restore it the filestore directory will be replace with the empty filestore directory, you will then copy the filestore backup folder over the filestore folder and make sure it have proper user:group access 

in the future, you should consider to create backup with .zip instead of .dump or if you want to backup using dump database you will have to backup the filestore separately

regard, 

Tuan 

https://skyerp.net